1  /* { dg-do compile } */
       2  /* { dg-options "-O2" } */
       3  
       4  typedef unsigned IPos;
       5  typedef unsigned char uch;
       6  extern uch window[];
       7  unsigned max_chain_length;
       8  unsigned strstart;
       9  int longest_match(IPos cur_match, int len, int best_len)
      10  {
      11      unsigned chain_length = max_chain_length;
      12      register uch *scan = window + strstart;
      13      register uch *match;
      14      register uch scan_end1 = scan[best_len-1];
      15      register uch scan_end = scan[best_len];
      16      do {
      17          ;
      18          match = window + cur_match;
      19          if (match[best_len] != scan_end ||
      20              match[best_len-1] != scan_end1 ||
      21              *match != *scan ||
      22              *++match != scan[1]) continue;
      23              best_len = len;
      24      } while ( --chain_length != 0);
      25      return best_len;
      26  }